Police intervened at Paris high schools today after five of them received a bomb threat by telephone around mid-morning, the Paris education authority said.

"The students are in the schoolyard and we are waiting for the bomb squad," said a spokesman at Louis Le Grand in the Saint-Germain-des-Pres area, one of the schools involved, which included some of Paris' best known elite academies.

No devices were found so far.

France is on high alert since militant Islamist gunmen and suicide bombers killed 130 people in and around Paris on Nov. 13.